1. Field of the Art
This invention relates to a method for testing frequency characteristics of laser displacement/vibration meters which are widely in use in industrial fields. A laser displacement/vibration is an instrument used to measure a displacement or a vibration of an object's surface using laser illumination and a process of reflected light. More particularly, this invention concerns a method for testing frequency characteristics of a laser displacement/vibration meter for the purpose of establishing traceability in the measurement of high-speed micro-level displacements and micro-level vibrations, by comparing measurement data of a laser displacement/vibration meter and a reference laser interferometer with a reference laser bean or a laser interferometer of a similar class, employing a novel technology for generating high-speed micro-level fine displacements or vibrations.
2. Prior Art
Laser displacement/vibration meters have thus far been in wide use in industrial fields for measurement of displacements and vibrations according to the principles of light-wave interference based on Doppler shifts and heterodyne light-wave interference. However, it has been infeasible to assess the reliability and accuracy of laser displacement/vibration meters of this nature due to absence of technology of generating high-speed micro-level fine displacements over a wide frequency range where the frequency is close to a DC component.
On the other hand, as evidenced by the developments in the so-called micromachine technology in advanced western countries, there have been increasing necessities for measuring movements of microstructures far smaller than conventional counterparts, over a frequency range broader than was necessary heretofore. It follows that severe requirements are imposed on a laser displacement/vibration meter especially on the reliability and accuracy of measurement. As a consequence, users and manufacturers of meters of this sort are in need of a new method for generating high-speed micro-level displacements or high-speed micro-level vibrations which are difficult to generate with conventional methods.